1. Technical Field
The present invention relates generally to plug-type aircraft doors; and, more particularly, to inwardly/outwardly movable plug-type aircraft doors of the type which are adapted to be translated between a first fully closed and latched position and a second fully open position while being maintained at all times in a plane essentially parallel to the plane containing the ingress/egress cutout opening formed in the aircraft fuselage--i.e., the aircraft door is not appreciably moved into the aircraft interior during any portion of a door opening/closing operation; nor is it pivoted or rotated about the hinge axis to, in effect, turn the door inside-out when fully open. Rather, aircraft doors embodying the features of the present invention are moved with translatory motion about a vertical, or near vertical, hinge axis, thus effectively limiting the need for imposition of the significant manual forces heretofore required to move relatively heavy aircraft doors in an uphill direction during significant portions of a door opening and/or closing operation when the doors are pivotally or rotationally mounted for movement about an inclined hinge axis. Since aircraft doors constructed in accordance with the present invention are intended to be operated about a vertical, or near vertical, hinge axis, the invention finds particularly advantageous use in connection with narrow-bodied commercial passenger aircraft where relatively constant fuselage frame cross-sections are available permitting mounting of one or more aircraft doors at various fore and/or aft locations.
2. Background Art
Conventional commercial aircraft are commonly provided with a multiplicity of ingress/egress openings in the aircraft fuselage with suitable doors being provided for closure of such openings. The doors vary widely in terms of their construction and operation. Commonly, such doors are plug-type doors which are designed to fit into the ingress/egress openings when the doors are closed so as to form a substantially smooth, continuous, uninterrupted, exterior skin surface. When such doors are opened, they may be moved through any of several different paths, dependent upon the particular door design employed. For example, some plug-type aircraft doors are of the type which move inwardly into the aircraft and slide upwardly along tracks deployed on the interior of the fuselage with the door being received within a compartment immediately above the ceiling in the passenger cabin. In still other instances, the doors are pivoted about the axis of a first torque tube assembly mounted in the door and moved slightly inboard, at which point the doors are pivoted simultaneously about the axes of both the first door-mounted torque tube assembly and a second torque tube assembly mounted in the fuselage body structure and to which the door is hingedly connected, with the door moving outwardly through the ingress/egress opening, and swinging through an arc approximating 180.degree. so that when fully open, the door is entirely disposed outside of the aircraft fuselage, lying in a plane generally parallel to the aircraft centerline and with the door's outer skin surface essentially in face-to-face contact with the outer skin surface of the fuselage--i.e., the door is, in effect, turned inside-out. In most instances today, doors of the foregoing character are manually operated by on-board flight attendants since most commercial aircraft carriers are reluctant to rely upon electrical actuating systems which are subject to electrical malfunction. As a consequence, and due to the rather significant weight of the doors and the limited strength of crew attendants, it has been necessary to provide rather sophisticated counterbalance systems so as to enable the on-board flight attendant to manipulate such doors, particularly when the doors are being moved along an uphill path--a necessity when the door's hinge axis is other than essentially vertical.
In recent years, some commercial aircraft have employed ingress/egress doors which are capable of translatory motion about a vertical, or near vertical, hinge axis, thus permitting the on-board flight attendant (or ground crew members located external to the aircraft) to open the door by translating the door outwardly with the door, when fully opened, occupying a position wherein the interior skin surface of the door is in facing relation to the exterior fuselage skin surface. Because the door is moved about a vertical, or near vertical, hinge axis, the door is in essentially a balance position during all portions of door opening and/or closing movement, thus effectively eliminating the need to move the door uphill and enabling even those on-board flight attendants having relatively low body weights and limited strength to manipulate doors weighing two, three or more times the body weight of the flight attendant with relative ease.
Nevertheless, outwardly opening translatory plug-type doors of conventional construction have continued to pose a number of significant problems for aircraft designers. One of the more significant of these problems is directly related to the requisite hinge mechanism and actuating linkages which are needed to interconnect the door to the aircraft fuselage frame structure. More specifically, with such constructions, the aircraft door is commonly supported in cantilever fashion from one end of a hinge assembly coupled to the fuselage frame; and, since the hinge elements and other associated operating linkages must, in effect, go around a corner as the door is moved towards a fully opened position, they have tended to be rather complex and, moreover, they tend to project into the ingress/egress cutout opening when the door is fully open, thus effectively reducing the size of an unobstructed door opening. Moreover, in some instances, the hinge assembly and/or associated actuating linkages limit the degree of permissable door opening movement. As a consequence of the foregoing problems, and in order to meet the specifications of commercial aircraft carriers, it has been necessary to make the cutout opening in the aircraft wider to accommodate laterally projecting components and/or somewhat higher to accommodate overhead projecting components while maintaining the necessary unobstructed ingress/egress opening in the aircraft. Compounding the foregoing problems is the requirement that such ingress/egress passenger doors in commercial aircraft be provided with deployable emergency evacuation systems and their associated actuating linkages.
As those skilled in the art are well aware, the prior art is replete with numerous patent disclosures dealing with the foregoing types of doors and their inherent problems. Exemplary patents which are representative of plug-type aircraft doors with associated deployable evacuation systems and of the type which are adapted to move upwardly along tracks into the interior of the aircraft fuselage are those disclosed in U.S. Pat. Nos. 4,125,235--Fitzgerald et al and 4,470,566--Fitzgerald, both of which are assigned to the assignee of the present invention.
Patents which typify outwardly opening plug-type doors of the type adapted to be rotated about either a vertical or an inclined hinge axis and which are, in effect, turned inside-out include U.S. Pat. Nos.: 2,997,751--McPherren; 3,051,280--Bergman et al; 3,791,073--Baker; 4,199,120--Bergman et al; and, 4,479,623--Maraghe et al. Reference to the Bergman et al and Baker patents, all of which are assigned to the assignee of the present invention, reveals the nature of the problem inherent with hinge mechanisms and associated actuating linkages which project into the ingress/egress cutout opening when the door is open; while the Maraghe et al patent, also assigned to the assignee of the present invention, is illustrative of the types of counterbalance systems that are required with such doors to enable on-board flight attendants to manipulate the doors along uphill paths.
Wilmer, U.S. Pat. No. 3,004,303 is of interest for its early disclosure of a rather rudimentary type of aircraft door of the type intended to move with translatory motion. The patent contemplates the use of a lower main hinge and an upper control member, each of which are pivotally connected at one end to the aircraft frame adjacent the ingress/egress opening and at their other ends to the approximate midpoint of the door, with the uppermost control member serving to maintain parallel movement of the door as it is translated to and from a fully opened position. It is believed that commercial aircraft employing translatory plug-type doors of the general type disclosed in the Wilmer patent have, of necessity, employed considerably more complex latching and locking mechanisms than shown in the patent.
Heinemann et al, U.S. Pat. No. 2,751,636, a patent assigned to the asignee of the present invention, discloses a similar translatory plug-type aircraft door construction, here employing upper and lower hinges defining an inclined hinge axis about which the door is translated, together with an overhead control linkage. The construction is such that when used with conventional narrow bodied commercial aircraft of the type presently being manufactured, the fuselage curvature prohibits disposition of the hinges for rotation about a vertical, or near vertical, hinge axis; and, consequently, this arrangement would further require rather sophisticated counterbalance systems and, in some instances, power assist systems.
Yet another patent illustrative of closures for aircraft ingress/egress openings which do not rotate is Russian Pat. No. 182,003, wherein a hatch closure is provided that is moved out of the ingress/egress opening and then moved sidewise along spatial runners.
Other patents of miscellaneous interest include Linderfelt, U.S. Pat. Nos. 3,085,297 and Allwright et al, 3,647,169.